Detecting device for wireless telegraphy.



R. A. PESSENDEN. DETECTING DEvIcE FOR WIRELESS TELEGRAPHY. APPLICATION FILED MAR. 26, 1907. RENEWED FEB. 11,1909.

917,574. Patented Apr. 6, 1909.

Fig.5. 1 20 21 23 Wilrzess: E. 2 1 7229 W @JM improve the operation of UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN, OF BRANT ROCK, MASSACHUSETTS.

DETECTING DEVICE FOR WIRELESS TELEGRAPHY.

To all 'w/iom it may concern:

Be it known that I, REGINALD A. FES- smvnnx, a citizen of the United States, residing at Brant Rock, in the county of Plymouth and State of Massachusetts, have invented a certain new and useful Detecting Device for \Vireless Telegraphy, of which the following is a specification.

My invention relatesv to the artof transmitting intelligence by electro-magnetic energy, and more particularly to detectors for the received oscillations.

The primary objects of my invention are, to utilize certain eifects upon conductors in moving frictional contact caused by electromagnetic Waves for detecting such waves; to provide a receiver of superior sensitiveness, uniformity of action and simplicity of construction; to adapt such receiver for amplifying and for making various kinds of records. of received waves, and to generally the receiving circuit. These objects, and other advantages which will hereinafter appear, are attained by apparatus such as shown forillustration in the accompanying drawings, wherein,-

Figure 1 is a diagran'nnatic view of the app iratus of a receiving station, the cup of liquid being shown in section. Fig. 2 is a plan. view of the apparatus. Fig. 3 illus 'trates a modified mode of recording the received signals.

It has heretofore been known that electromagnetic waves have an effect upon the conductive contacts of various substances, including metal-and-liq'uid contacts. According to some theories this is due to electrolytic action and according to others it is due to ohmic resistance in still others a contact of an oil covered liquid metal and a solid metal have been used on the theory that the insulating film between the two is broken down by the waves so as to lessen the resistance of the contact. I have discovered however, that a solid conductor moving in a liquid conductor will have the degree of friction between the two altered by the action of the waves, and I apply this principle to the construction of a very sensitive detecting receiver. Thus, as shown for illustration in the figures, there is provided a vessel 4 for containing a liquid 5 having conductive qualities, and in this liquid is projected a small body such as a barreter wire 6, carried on a light aluminum arm 7 and supported pivotally by a sensitive tor- Specification of Letters Patent. Application filed March 26, 1907, Serial No. 364,626.

Patented April 6, 1909. Renewed February 11, 1909. Serial No. 477,453.

from the generator 13.

The vessel 1 and its shaft 10 are mounted upon a base 16, and by means of a pulley and band. 17 or other connection, the motor or clock work 18 keeps the vessel 4 111 uni form rotation at the desired speed. The

vessel may have baflle plates 19, or other devices to insure the traveling of the liquid with the rotation of the vessel, and the amount of immersion of needle 6 is regulated by screw 10 In this apparatus, the oscillations received in the antenna A would pass to the ground ordinarily by way of the torsion wire 8, arm 7, needle 6, liquid 5 and wire 9,-supposing there was no local circuit, or the contact between the arm 7 and the point 14 is broken. The speed of the vessel is so regulated that the friction of the liquid on the needle 6 will drag it along and turn the arm 7 so that its other end will be out of contactwith the point 14. If a signal is received however, the waves cause a change in the condition of friction between the needle 6 and the liquid allowing the torsion stress of wire 8 to swing the arm 7 so as to make contact at 1 1, whereupon the local circuit is closed and the relay 17 will give a signal. Otherwise, as indicated in Fig. 3, the arm 7 may by its swingingmove a recording point 20 over a record tape being translated under it by means of rollers 22 driven by a motor thus making a pcrnmnent. record of the signals directly. Or again, a small mirror as 2 on the arm 7 may be used in any of the well known galvanomctcr methods for making the signals. Various other means for detecting the movements of the torsion arm may be used, the essence of the invention being applicable to many forms of specific apparatus, and of course is not limited to that shown.

' The invention in its broader aspect, as comprising two relatively moving conductors, in frictional contact and indicating means operated by the changes in the frictional stresses due to the passage of oscillating currents therethrough, is not herein 1. A receiver for electro-ma etic waves comprising a conducting liqui and a conducting body projecting thereinto, the two having relative motion, means for movably supporting said body so as to balance it against the frictional stress of the liquid, and means for indicating its movements due to alterations in' said stress by the waves.

2. In a receiver the combination of a moving liquid, a terminal supported in electrical contact-therewith, means to yieldin ly mount the terminal to resist the frictiona stress of the liquid and means to give a si a1 when the position of the terminal alters y change in said friction due to electro magnetic waves.

3. In a receiver the combination of a body of conducting liquid, a terminal mounted in a torsion balance and projecting in the liquid, means to maintain continuous movement of the liquid against 'the terminal to balance the friction stress, and means to detect movements of the terminal due to waves, substantially as described.

In testimony whereof I have hereunder signed my name in the presenceof the subscribed witnesses.

REGINALD A. FESSENDEN.

Witnesses Jnssns E. BENT, ADELEINE WOLEVER. 

